Kids, do not try this at home!

class_generation.py

#!/usr/bin/env python2.7

""" class_generation.py: This file generates subclasses of
    GeneralPurposeClass in execution time just for the fun 
    of it.

    >>> import class_generation
    >>> for class_name in class_generation.__all__:
    ...     instance = eval("class_generation.%s" % class_name)()
    ...     instance.greet()
    ... 
    GeneralPurposeClass: GeneralPurposeClass reporting for duty!
    FooClass: I just say hello!
    BarClass: reporting for duty is boring!
    >>> 
"""

__all__ = ['GeneralPurposeClass']

class GeneralPurposeClass(object):

    greeting = "GeneralPurposeClass reporting for duty!"

    def greet(self):
        print "%s: %s" % (self.__class__.__name__, self.greeting)

class_definition = [
    {
        'class_name': 'FooClass',
        'greeting': 'I just say hello!'
    },
    {
        'class_name': 'BarClass',
        'greeting': 'reporting for duty is boring!'
    }
]

for class_declaration in class_definition:
    vars()[class_declaration['class_name']] = type(
            class_declaration['class_name'],
            (GeneralPurposeClass, ),{
                'greeting': class_declaration['greeting']
            }
        )
    __all__.append(class_declaration['class_name'])